trawl – gear description (fish & shrimp) · 2013. 2. 18. · references eayrs, s. 2007.a...

INSERT INSTRUCTOR Name

Trawl – Gear description (fish & shrimp)

http://www.safmc.net

Joël Prado - FAO/FIIT http://www.whboat.com

Introduction Fish & invertebrates Bottom (demersal) and midwater (pelagic)

http://www.ilvo.vlaanderen.be http://www.seafish.org

Introduction Fish & invertebrates Bottom (demersal) and midwater (pelagic) ~ 50% global catch

Watson et al. 2004

Introduction Fish & invertebrates Bottom (demersal) and midwater (pelagic) 50% global catch Active Cone-shaped net

http://www.montereybayaquarium.org

http://research.usm.maine.edu/

Introduction Fish & invertebrates Bottom (demersal) and midwater (pelagic) 50% global catch Active using cone-shaped net Small & large vessels

NOAA Fisheries http://www.crenvironmental.com/NOAAtrawl.htm

Introduction - Impacts Bycatch Juvenile fish in shrimp trawl Protected species

Bottom habitat

Shrimp fishing bycatch (Madagascar) http://www.ird.fr/

Before (top) & after (bottom) trawling. FAO 2005

Objectives Describe how trawl gear works List 4 components of a trawl and describe 2

pieces of specialized equipment Demonstrate ability to complete the gear

description form

Sampling Priorities 1. Collect information on fishing effort 2. Randomly sample catch for catch composition 3. Record gear characteristics 4. Collect length-frequency data on target and

non-target catch

Trawl configurations Varies by target & fish behavior Beam trawl /otter trawl / pair trawl

Trawl configurations Varies by target & fish behavior

Beam trawl /otter trawl / pair trawl

http://www.scotland.gov.uk/

http://www.qc.dfo-mpo.gc.ca/ Griffiths: http://www.sanctuarysimon.org/


Beam trawl /otter trawl (animation from http://www.dantrawl.com) / pair trawl

http://www.liv.ac.uk/

http://www.crimond.com/bison.htm

http://www.dantrawl.com/�


Beam trawl/otter trawl/ pair trawl(2 vessels)

Photos: http://www.boatdesign.net/forums/open-discussion/beam-trawl-query-17413.html

http://www.nfrdi.re.kr http://news.bbc.co.uk

Trawl configurations

Images modified from FAO (2001b),Lokkeborg (2005) and http://www.crimond.com

http://www.crimond.com/

Trawl configurations Confusing terminology (#1)

Pair trawl – 2 vessels

Twin trawl – 2 nets

Duplex (separator) trawl –

2 codends

http://www.nfrdi.re.kr


Trawl configurations Confusing terminology (#2)

Beam trawler –vessels which

deploy nets from abeam; also outrigger trawler or winch boat Beam trawl – type of net

Beam trawler with beam trawls; http://www.ilvo.vlaanderen.be

Net components (Manual Fig.6-2)

Net components (Manual Fig.6-3)

Sack

Headline

Net configuration

Fisheye BRD

Tie off rings

TED (hard grid)

Elephant ears

Headrope / headline

Lazy line

Footrope

Dummy door Trawl door

Tickler chain

Bottom leg Top leg

Floats

Guide line

Gear Deployment & Retrieval Video - retrieving

NOAA Fisheries

Bycatch reduction Bycatch reduction device (BRD) Junk fish excluder (JTED) Turtle excluder device (TED)

NOAA Fisheries http://www.gbrmpa.gov.au

Bycatch reduction Bycatch reduction device (BRD) Junk fish excluder (JTED)

NOAA Fisheries

Fish eye (http://www.seagrantfish.lsu.edu)

Square mesh window (FAO)

Square mesh codend

(http://bayjournal.com.au)

Radial escape section (http://www.seagrantfish.lsu.edu)

Bycatch reduction Bycatch reduction device (BRD) Junk fish excluder (JTED) Turtle excluder (TED video)

w

NOAA Fisheries Photo: Mike Gerner, AFMA

http://www.euroturtle.org

Bycatch reduction

Trawl sensors

http://www.notus.ca/

Gear Description - Finfish

X

http://dnr.louisiana.gov/


http://www.net-sys.com/

www.morgere.fr/


Headline


http://www.eurorock-belgium.com

http://www.cosmostrawl.dk

http://www.fao.org/

Courtesy of S. Sei, Sierra Leone)

StretchedMeshOpening -Diamond Mesh




Fish eye (http://www.seagrantfish.lsu.edu) Images from Eayrs (2007)

x


x

Radial Escape Section(http://www.seagrantfish.lsu.edu) Images from Eayrs (2007)

Gear Description - Finfish X Images from Eayrs (2007)

Gear Description - Shrimp

Gear Description - Shrimp

Grid angle

Activity Handout Groups of 2 or 3 20 minutes *use mini net in front of room for your codend mesh size.

Record your measurements and average mesh size calculation.

FS345 LIB 9997 7 x

1 x

x Crimond nova demersal

2.4 2.0 1000

4.03 1.2 chain 3. 5 1.2 chain 4.2 1.2 chain 6 20 wire cable 7.2 15 wire cable 6 15 wire cable

Length = 2.4 m

Hei

ght =

2 m


400 25 steel cable

52 20 nylon 18 60 22 weighted synthetic 11 60 Dyneema 65 10 chain (sttel) 100kg


8 25 rubber 15 15 10 rubber 32

Polyethelene 3.5 15.0 25 100 Polyethelene 3.5 12.0 30 65

Polyethelene 3.5 8.25 W 110 76

x

x

Summary Can you name the trawl configurations below

Beam trawl / otter trawl / pair trawl

Summary

1

1

2

3

3

4

4

Summary

Describe how trawl gear works

References Eayrs, S. 2007. A Guide to Bycatch Reduction in Tropical Shrimp-Trawl

Fisheries. Revised edition. Rome, FAO. 108 p. Kelleher, K. 2005. Discards in the world's marine fisheries: An update. FAO

Fisheries Technical Paper, FAO, Rome. Watson, R., E. Hoshino, J. Beblow, C. Revenga, Y. Kura, and A. Kitchingman.

2004. Fishing Gear Associated With Global Marine Catches. Fisheries Centre Research Reports 12.

trawl – gear description (fish & shrimp) · 2013. 2. 18. · references eayrs, s. 2007.a...

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